A “ground” is an electrical connection between a circuit or equipment and the earth or a large conducting body that serves in place of the earth. “Grounding” an electrical system is installing a ground in the electrical system. The safe return of errant current (also called “fault current”) to the earth without damage to life or devices is an important concern of businesses, utilities, and homeowners. When a ground fails, valuable assets can be destroyed and people can be injured or killed. In the United States, the National Electric Code (NEC) requires a protective ground to prevent voltage build-up from a lightning strike, short in a circuit path, or insulation failure that would otherwise cause electrical shock, injury, or death. In an industrial setting, the absence of a very low-resistance grounding path can cause a build-up of static electricity which, in turn, can introduce noise into communication and transmission circuits and can present a danger when handling flammable materials. Grounds protect electrical equipment or systems from reaching excessive voltage by providing an alternate path for current to travel (other than through an electrical circuit in the equipment). Grounding is also valuable for preventing electric shock hazards. A neutral wire connecting electrical equipment to a ground system of a structure prevents development of large voltage differences between the neutral line and a ground line leading from the ground pin of a plug to the chassis of the equipment.
Ground rods, also known as ground electrodes, are typical mechanisms for establishing a ground connection to earth. Rods constructed of copper or iron, each typically having an 8-foot length, are driven into the ground and then electrically connected to a source of the current that is sought to be grounded (fault current source). Such rods cannot be used in all types of terrain because in some areas, the soil depth is much less than 8 feet, so in such areas horizontal grounding grids (comprising ground rods buried horizontally) are used to cover large areas. Such grounding grids are less reliable than ground rods because when a grounding element such as a grid or rod is buried horizontally, almost half of the grounding capacity is wasted, as the surface area of the element facing upwardly in the soil will only be able to affect the conductivity of the little soil that is above the buried element. Another drawback of existing systems concerns variances in soil moisture. Ground rods typically need to interact with some moisture to be effective. However, some soils can be situated in arid environments, or areas experiencing a drought, and in those cases, ground rods are typically not able to function as intended. Furthermore, different sites have different compositions as well as different soil depths. For example, soil near a coastline can have brackish water in it, which can conduct current at a very low resistance (between one and two ohms), whereas only around 10 miles inland, the soil often lacks brackish water and the resistance can radically increase to as much as several hundred ohms. Such differing conditions have often caused each installation of a grounding system to be specifically designed for each site, with little or no uniformity between installations at different sites.